I have heard people say that the Five Books of Moses had to be divine and written 3-4kya because there is content in it that later writers (a la Documentary Hypothesis) simply could not have known. I'm unsure what specifically that includes, perhaps some details of culture of Bronze Age Ur or Egypt. Could it have been written by ordinary scribes in the Iron Age, or are there actually specific details that could have only been known at one point in time?

If I'm not mistaken, you're referring to the medical knowledge implicit in some of the Mosaic law. The standard Apologetic argument goes that long before modern medical knowledge, God gave Laws relating to cleanliness and avoiding disease and other scientific knowledge that was well ahead of its time.

For centuries doctors denied the possibility that disease could be
transmitted by invisible agents. However, in the late 19th century
Louis Pasteur demonstrated in his Germ Theory of Disease that most
infectious diseases were caused by microorganisms originating from
outside the body. This new understanding of germs and their means of
transmission led to improved sanitary standards that resulted in an
enormous drop in the mortality rate. Yet these core principles of
sanitation were being practiced by the Israelites thousands of years
earlier.

The Israelites were instructed to wash themselves and their clothes in
running water if they had a bodily discharge, if they came in contact
with another person's discharge, or if they had touched a dead human
or animal carcass. They were also instructed to wash any uncovered
vessels that were in the vicinity of a dead body, and if a dead
carcass touched a vessel it was to be destroyed. Items recovered
during war were also to be purified through either fire or running
water. In addition, the Israelites were instructed to bury their human
waste outside of camp, and to burn the waste of their animals (See
Numbers 19:3-22, Lev. 11:1-47; 15:1-33, Deut 23:12).

Circumcision and Blood Clotting

For centuries scholars must have been perplexed by God's law of
circumcision which required the procedure to be performed on the 8th
day after birth (Gen 17:12, 21:14, Lev 12:3, Luke 2:21). Medical
researchers recently discovered that the two main blood clotting
factors, Vitamin K and Prothrombim, reach their highest level in life,
about 110% of normal, on the 8th day after birth. These blood clotting
agents facilitate rapid healing and greatly reduce the chance of
infection. You can verify with any Obstetrician that the 8th day of
life is the ideal time for a circumcision, and that any circumcision
done earlier requires an injection of Vitamin K supplement.

If you move beyond the Pentateuch and into other Old Testament books, there are other scientific statements that don't match up with the beliefs of Pagan societies at the time.

The Earth and Space

The earth's shape is perhaps the most important to deal with first
since many critics claim that the Bible portrays the earth as flat.
This couldn't be farther from the truth and in my opinion is one of
the most vaporous arguments used by skeptics against the Bible. There
is not a single passage that plainly states that the earth is flat1.
The groundswell of this criticism gets its roots from the inaccurate
but common belief among many that the ancients on up through the
middle ages believed that the earth was flat. The truth is, virtually
all learned people have known for the last 2500 years that the earth
is spherical [please see footnote 2].

Before the learned ancients surmised that the earth was spherical, the
divinely inspired Isaiah wrote "It is He who sits above the circle of
the earth...(Isaiah 40:22)". In addition, from the Book of Job we have
"He stretches out the north over empty space; he hangs the earth on
nothing (Job 26:7)". It should be noted that just last century
scientists believed space consisted of a hypothetical substance called
Ether (not the chemical), which was the medium between the celestial
bodies. Also, the pagans of that time believed in such things as a
mythical Atlas character who supported the pillars that held heaven
and earth apart, and later carried the earth around on his shoulders.
Another interesting tidbit that illuminates the divine nature of Job
26:7 is the recent discovery of a huge hole in space in the direction
of the northern hemisphere3.

and...

The Hydrologic Cycle

The circulation and conservation of earth's water is called the
hydrologic cycle, which is accurately portrayed in several passages of
the Bible, including the following: "For He draws up drops of water,
which distill as rain from the mist, which the clouds drop down and
pour abundantly on man. (Job 36:27-28)" . Centuries after the Book of
Job was written, Aristotle demonstrated only a vague understanding of
this process. Though he recognized that rain came from clouds, he
incorrectly postulated that air turned into water and vice versa.

There are more, and the site I linked to covers them in more depth, as does this site. Putting them all here would be counter-productive (and plagiarism) so I'll stop there.

Sorry, I thought it was implicit in my question that it is only about details that have later been verified scientifically, for purposes of validating or falsifying the Pentateuch. Whether Cain killed Able or not isn't something we can know even today.
–
AaliyahNov 14 '13 at 23:09